The research project on the organism Saccharomyces cerevisiae will include the following: 1) The regulation of maltase induction in yeast will be studied at the molecular level along the following lines: the cloning of the regulatory and structural genes to determine the number of structural genes, the organization and location of the regulatory and structural genes; the mechanism of catabolic repression of maltase induction by glucose; the overall steps of maltase induction, following transcription and processing of maltase mRNA by hybridization and by in vitro translation of the transcripts. 2) The expression of heterologous genes in yeast. Recombinant DNA technology and transformation has made it possible to introduce a variety of cloned genes into yeast. The bacterial chloramphenicol resistance (Cm1) gene is expressed in yeast, coding for the enzyme chloramphenicol transacetylase (CT). Yeast strains transformed with the Cm1 gene on an integrative plasmid are resistant to low levels in the antibiotic; yeast mutants can readily be generated with increased levels of resistance. Two classes of such mutants are of interest, and include those that are associated with the plasmid carrying the CM1 gene and those that are chromosomally located. Work in progress and being planned includes: the comparison of the CT mRNA generated in E. coli and yeast; the genetic and biochemical characterization of the mutants with increased levels of CT activity; the differences and similarities of expression of the CM1 gene (and its mutants) in bacteria and yeast. 3) The characterization of yeast glycolytic mutants. The mutants, especially those affecting pyruvate decarboxylase, triosephophate isomerase, phosphoglucose isomerase and fructose biphosphatase will be characterized genetically and biochemically wih respect to the nature of the mutations (whether they are regulatory or structural). The structural mutants will be used in transformation experiments to clone the wild type alleles.